Control mechanism for press brakes or similar machines



Nov. 7, 1944. G. BATH 2,362,343

CONTROL MECHANISM FOR PRESS BRAKES OR SIMILAR MACHINES Fil ed Feb. 6 1942 2 Sheets-Sheet 1 I I. v 6'4 2 46 27 2.9 F

INVENTOR. C'yem I 5477-1. BY M 44. %/M

ATTORNEY.

c. J. BATH 2,362,343 CONTROL MECHANISM FOR PRES S BRAKES OR SIMILAR MACHINES Nov. 7, 1944.

Filed Fb. s, 1942 .1 l/Z H 2 Sheets-Sheet 2 INVENTOR. (we/4 J 5/: 7H

Patented Nov. 7, 1944 UNITED; STATES CONTROL MECHANISM FOR PRESS BRAKES A on SIMILAR MACHINES Cyril J. Bath, Hudson, a.

This invention relates generally to' control mechanisms forpress brakes or similar machines having a die carrying 'slideor ram which is reciprocated towards and away from a stationary die support or bed.

In machines of this character a blank is shaped "between'two cooperating dies, one of which is secured to'the stationary die support'or bed and the other of which is carried by the reciprocating slide or ram. .W'hen ablank is being shaped beli) tween .the dies, as -the movable die. approaches the stationary die, the frame'of the machine is stretched. The amountthe frame is stretched is dependent'upon the nature of the work being done, the setting 'ofthe dies, and the thickness of the blank If the frame is stretched beyond a certain pointitwillbe injured or broken. As

most machines of this character are capable ofexerting a force suflicient to injure or break the frame or ,other. parts of the. machine, extreme" care must be taken in selecting the work for the machine and insettingand adjusting thedies, so the machine will not.be,. overloaded.- It has been found by experience that even though great care is exercised in operating machines of this character they are frequently injured or broken.

This is caused by various differentconditions of operation. The dies may get out of adjustment or a thicker blank than that for which the dies are set may be encountered or something'may ac- 0 cidentally, and unknown to the operator, get between the dies. -Machines have been broken when a newset of dies are being installed and adjusted. a

In order to eliminate any possibility of injuring the machine dueto overload I have incorporated into my control mechanism a safety device for automatically stopping the operation of the machine when a certain predetermined load is reached. This safetydevice utilizes-the inher- '40 ent stretching of the frame and operates to-throw out the clutch and disconnect the drive from the slide or ram, when the frame has been stretched a predetermined amount. This safety device functions only-when the. 111101301 is running in 4:5.

onedirection, as I have also providedmeans for rendering it'ineffective to disengage the clutch. when the motor is running in the reverse direction. This makes it possible to reverse the motor p and back the ram away from the work after the machine has been stopped due to an overload.

The construction of my control mechanism is such that it canbe easily and cheaply manufactured and yet is very' eflicient and reliable .in'operation and can be readily applied to machines Application February 6, 194;, Serial no. 429.735

"9 Claims. 401392-) .now in use without requiring'extensive changes theretol. In the followingjspeciiication and the drawings forming a part'thereof I have illustrated and "described one embodiment of myjinvention as construction. V

In the drawings: 1

Fig. 1 is a-perspective view of a press brake having my invention applied thereto;

Fig. 2 is an end'elevation, on a somewhat larger applied to a press brake of well known standard scale, of I the rightr han'd endof the press brake shown in Fig. 1; t I n i Fig. 3 is a section throughthe flywheel, clutch andbrake, taken substantially on the line 3-3 Fig. 4 is' an enlargedjdetail side elevation of that part of mycontro'l mechanism which dis Iconnects the fo0ttread1efr0m the/rest of the clutch 'operatin ,.mechanis m when the press brake has been subjected to an Overload; and

Fig. 5 isfa wiring. diagram showing the various electrical circuits forming apart of my control mechanism.

Referring to the drawings reference "characters, A indicates generally a standard pressbrake having a frame made up of. steel plate suitably welded together. The frameconsists of a pair of spaced uprights l0,.the 1ower:ends of which are connected together by. a front plate I I, which has a .dielsupport I 2, weldedor otherwise suitablylsecured to the upper edge thereof. The

,I upper surface of. the dieplate l2 forms the supporting surface or abutment forthe lower stationary die or punch'l3, as the case may be. .The

upperv movable diejor punch. I6 is connected to the lowerlend of a slideor ram I'I'slidablysup- ..Dorted above the-die plate l2 and adaptedto be .recipro'jc'ated towai dandfrom the sameby a suitable ,crankQmechanism. The mechanism shown for reciprocating the ram ll comprises I adjustable pitmans 1L8 connected to the ram 11 and to suitable cranks on crank-shafts .I9 rotatably. supportedfin the frame A.. The crankshafts I 9 are adapted to be rotated or driven-by a three-phase alternating currentv electric motor 20 of conventionalconstruction housed within the frame A and operatively connected by afiexible drive connection 22 to a pulley 23 bolted to clutch 26, alternate disks of which are keyed to the inside of the pulley 23 and to a member 21 keyed to the shaft 25.

The disks of the clutch 26 are adapted to be clamped together by bell-crank levers 28 pivotal- 1y connected to bosses 29 formed integral with the member 21. One end of each of the levers 2B is adapted to engage the outer disk of the clutch 26, as viewed in Fig. 3, while the opposite ends thereof are connected by links 30 to a member 3i slidably supported on the shaft 25 and adapted to be moved therealong by a forked member 32 adjustably fixed to one end of a rod 33 slidably but nonqotatably carried by a bracket 34 bolted to the frame A. The rod 33 is continuously urged towards the right as viewed in Fig. 3 by a compression spring 35 interposed between the right-hand side of the bracket 34 and a washer 36 held in position on the rod 33 by a nut 31 which also provides means for adjusting the tension of the spring 35. The rod 33 is adapted to be moved towards the left, as viewed in Fig. 3 against the action of the spring 35 to engage the clutch 26 by a bell-crank lever 36 pivotally connected to the bracket 34, One arm of the lever is forked and engages a pin 39 fixed in the rod 33. The other arm of the bell-crank lever 38 is operatively connected by an adjustable link 40 to a lever 4| pivoted on the frame A. The lever 4| is in turn connected to a lever 42 by a link 43. The lever 42 is fixed to one end of a shaft 44 rotatably supported in the frame A and extending across the front of the machine. The shaft 44 is hexagonal or irregular in shape and carries a treadle 45 which is slidable thereon. This construction allows the treadle 45 to be located at the most convenient place, depending upon the particular work being performed by the crank-shafts I9 by pinions 49 fixed to the shaft 48 and gears 50 fixed to the crank-shafts I9. When the treadle 45 is depressed by the operator, the rod 33 is shifted to the left as viewed in Fig. 3 and the clutch 26 engaged. The ram I1 is thereupon reciprocated. When the treadle 45 is released, the rod 33 moves toward the right as viewed in Fig. 3 under the action of the spring 35, disengaging the clutch 26. Simultaneously with the disengagement of the clutch 26, a friction disk brake 5| applied to the shaft 25 is engaged so as to rapidly bring the ram .IT to a stop. This brake is somewhat similar in construction to the clutch 26 and consists of a plurality of disks, alternate ones of which are keyed to a member 52 bolted to the frame A and to a member 53 keyed to the shaft 25. The disks are clamped and released by a slidable member 54 and toggle mechanism 55 similar to that employed to actuate the clutch 26. The member 54 is operatively connected to the left-hand end of the rod 33 by a forked member 56, similar to the member 32, and adiustably connected to the rod 33.

From the foregoing it will be apparent that the clutch 26 will be held engaged against the action of the spring 35 and the ram I1 reciprocated as long as the treadle 45 is depressed by the operator; and that the clutch 26 will be disengaged and the brake 5! applied by the spring 35 when the operator releases the treadle 45, which will stop the movement of the ram.

In order to prevent injury to the press due to an overload I provide a safety device for automatically disconnecting the treadle 45 from the rod 33 when a predetermined force is exerted by the ram. As previously stated this safety device utilizes the stretching of the frame which is inherent in all machines of this type.

As shown in Fig. 4 the upper end of the link 43 includes a cylindrical member 60 slidably supported in a bore 61 in a member 62 which in turn is pivotally connected to the lever 41 by a pin 63. The members 60 and 62 are normally held in fixed relationship with respect to each other by a transversely extending pin or rod 64 which has one end slidably supported in a transverse bore 65 in the member 62 which opens into the bore 61. The other end of the rod 64 is slidably supported in a bore formed in a bracket 66 which is bolted to the member 60. The inner end of the rod or pin 64 is cone or wedge-shaped and normally engages in a cone or wedge-shaped notch in the member 60. The pin or rod 64 has an enlarged disc 61 formed integral therewith about midway between its ends through the medium of which the cone or wedge-shaped end of the rod is held in the notch in the member 60 by a lever 68 pivotally connected to the member 62 by a screw 69. The lower end of the lever 68 as viewed in Fig. 3 is provided with a latch. 10 that normally engages behind the enlarged disc 67 of the pin or rod 64 and maintains the same in its normal position. The lever 68 is adapted to be rotated in a counterclockwise direction about its pivot 69, to release the pin or rod member 64, by a solenoid I I, the armature 12 of which is operatively connected to the upper end of the lever 68 by a link 13. A small spring 14 is con nected to the lever 68 and a pin 15 fixed to the member 62 continuously urges the lever 66 in a direction to engage the latch 10 behind the en larged disc 61 on the pin or rod 64.

Energization of the solenoid (I is controlled by micro switches 16 and I1 operatively connected in a parallel circuit with each other and in a series circuit with the solenoid H. The micro switches 16 and 11 are normally open switches and are located at opposite ends of the machine. Both switches are alike and are operated in the same manner so only the one visible in the drawings will be described in detail. The contacts of the micro switch 16 located on the right-hand end of the machine are normally open but are adapted to be closed by an adjustable abutment l8 fixed to the lower end of a U-shaped member 19 the upper end of which is connected to a pin fixed to the frame A above the crank shafts I9. The U-shaped member 19 spans the throat of the end members or side frames of the press brake in such a manner that when the press is subjected to overload and the side frames or end plates ID are stretched, the abutment member 18 is raised with the result that when the overload reaches a predetermined amount the contacts of the micro switch 16 are closed, the solenoid H energized, and the latch 68 moved away from the enlarged disc 61 of the pin or rod member 64, with the result that the pin or rod 64 is free to move and release the member 60, or in other words, disconnect the members 60 and 62. A bolt 8! provided with a cylindrical inner end 82 which engages within a slot 83 in the member 60 allows the parts 60 and 62 to move apart a sufficient distanceto release the clutch 26 while maintaining the same in assembled relationship. Thelower end ofthe U-shaped member 'l9 is held in position by a pin 85, carried by the'end plate I0, which projects through an elongated aperture 86 in the member I9. This construction holds the member 19 in position without interfering with its operation. If desired, a micrometer dial gauge 81 graduated either in thousandths of an inch or in tons stress applied by the ram may be fixed to the end plate I in such a manner that its operating plunger-engages either theupper surface of the lower end of the member-19 or an adjustable abutment member connected thereto. calibrated in tons stress applied by the ramis very helpful in adjusting the overload'at which the micrometer switch or switches are actuated to release the driving clutch 25. The micro switch 11 is located at the opposite end of the press and is operated in a similar manner. The constructionis such that the clutch 26' will be disconnected in the eventeither of the end members or frames of the machineis subjected to strain beyond a predetermined safe amount. v

1 Power for operating the solenoid 'I'I is-obtained from the motor control panel 90 in such a manner that the solenoid II will beenergized upon clos ingot either of the micro switches 16 and 11 only the event that the drive motor is con.- nected to the power lines 9|, 92 and 93 in a manner to rotate in the forward direction. This allows the motor to be reversed and the ram backed off "the work in the event that the machine is stoppeddue to overload, without the use of supplemental means for rendering the safety feature inoperative. V

Reference to the wiring diagram, Fig. 5, will show that the electric circuit for the solenoid II is from the power line 92 through the line 94,

A device of this character that the objects heretofore enumerated and others have been accomplishediand" that there has claim is:

normally open contacts of one or the other or both of the-micro switches I6 and I1, line 95, solenoid II, line 96, contact bar 91 of motor control panel 90 and wire 98 to line 9I. The contact bar 91 is operated simultaneously with the contact bars I00, ml and I02 which connect the drive motor with the power lines in such a manner that'the motor rotates in a forward direction upon energization of the operating solenoid I03,

which solenoid is adapted to be energized by a norm-ally open push button switch I04 located at some convenient point on the machine. When the solenoid I03 is energized, a holding circuit is established by the closing of contact bar I05 which maintains the solenoid energized after the push button switch I04 is released. A normally closed stop push button switch I06 provides means for stopping the motor 20 at any time.

The drive motor can be rotated in the opposite direction by closing a normally open reverse push buttonswitch I01 which when closed energizes a solenoid I09 which in turn actuates the contact bars IIO, III, H2 and H3, the first three of which connect the motor 20 to the power lines in such a manner that it rotates in the reverse direction while the latter establishes a holding circuit for maintaining the solenoid I09 energized after the push button switch I0! is released. It will be observed that when the motor is operated in the reverse direction the circuit to the solenoid II is opened at the contact bar 91 ,irrespec-- tive of whether the contacts of the micro switches 16 and 11 are opened or closed.

From the foregoing description of the preferred embodiment of the invention, it will be apparent been provided'a novel and improved control mechanism for crank-operated machines such as press brakes and the like, which is inexpensive in construction, reliable in operation and which can-be readily applied to "existing commercial machines without requiring any extensive changes therein; and that there has also been provided-a novel and-improved means which will made in'the construction of m control 'mecha-' nism as illustrated and describedherein without departing from the scope of the invention as pointed out in the following claims.

Having thusdescribed my invention, what'I 1., A control mechanism for a press brakehaving a frame and a ramwhich 'is driven through a clutch; said control mechanism comprising manually operable means for holding said clutch in-driving engagement, and means associated with saidframe and said firstmenti'oned means and operableto render said first mentioned means ineffectiveto hold said clutch in driving engagee ment when the framehas been stretched beyond a predetermined point.

2 A control mechanism for a press brake having *aframe and a ram which is driven by a reversible motor through a clutch, said control mechanism comprising manually operable means for holding said clutch in driving engagement, means associated with said manually operable means and said frame and operableto render said manually operable means ineffective to hold said clutch in driving engagement after said frame has been stretched beyond a predetermined point with the motor running in one direction, and means operable to render said second mentioned means inoperative when the motor is rendered effective to run in the reverse direction.

3. A control mechanism for a press brake hav-v ing a frame and a ram which is driven by a reversible motor through a clutch, said control mechanism comprising manually operated means for holding said clutch in driving engagement, I

means associated with said frame and said manually operable means and operable by the stretching of the frame beyond a predetermined point when the motor is running in one direction to disengage said manually operable means from said clutch, and means operable to render said last mentioned means inoperative when the motor is rendered efiective to run in the reverse direction;

4. A control mechanism for a press brake having a frame and a ram which is driven by a reversible motor through a clutch, said control mechanism comprising manually operated means for holding said clutch in driving engagement,

electrically operated means for disengaging said manually operated means from said clutch, means operated by the stretching of the frame beyond I a predetermined point when the motor is runnine in one direction for rendering said electrically operated means operative to disengage said manually operated means from said clutch, and means for rendering said last mentioned means ineifective when the motor is rendered effective to run in the reverse direction.

5.. A. controlv mechanism'forwa press brake having a frame and a ram which is driven by a reversible motor through a, clutch, said control mechanism comprising manually operated means including two disengageable members for holding said clutch in driving-engagement. a latch for locking said disengageable members together, electric means associated with said frame and said latch and operable by the stretching of the frame beyond a predetermined point to release said latch and disengage said disengageable members.

6. A control mechanism for a press brake having. a ram which is driven through a clutch, said control mechanism comprising a. spring for disengaging the clutch, mechanism for engaging the clutch against th action of the spring, said mechanism including an expansible link consisting of two telescoping members, interengaging means between said telescoping members for looking them together so that they will move in unison, and means operable to disengage said telescoping members so that they-may move indepently of each other when the press brake exerts a pressure beyond a predetermined amount.

'2. A control mechanism for a press brake having a frame and a ram which is driven through a clutch, said control mechanism comprising means for holding said clutch in engaged position, said means including two telescoping members, a latch carried by one of said members for locking said telescoping members together so that. they will move in unison, means for disengaging saidlatch to render said mechanism inoperative to hold said clutch engaged when the press. brake has been loaded beyond a predetermined amount, said last mentioned means comprising a solenoid carried by one of said telecoping members and operatively connected to said latch, a switch operable when closed to energize said solenoid, and means secured to said frame and operable to close said switch when the frame has stretched beyond a predetermined amount.

8. A control mechanism for a press brake having a frame and a ram which isdriven by a reversible motor through a clutch, said control mechanism comprising means for holding said clutch in driving engagement, electrically operated means for rendering said clutch holding means ineffective to hold said clutch in driving engagement, means operated by the stretching of the frame beyond a, predetermined point when the motor is running in one direction for rendering said electrically operated means operative to render said clutch holding means ineffective to hold said clutch in driving engagement, and means for rendering said last mentioned means ineffective when the motor is rendered elfective to run in the reverse direction. 9; A. control mechanism for a press brake having a frame and a ram which is driven through a,

. clutch, said control mechanism comprising means for holding said clutch in engaged position, said means including two telescoping members, a latch carried by one of the said members for locking said telescoping members together so that they will move in unison, means for disengaging said latch to render said mechanism inoperative to hold said clutch in engaged position, said last mentioned means comprising a solenoid carried by one of said telescoping members and operatively connected to said latch, and automatic means for energizing said solenoid, when the press brake has been loaded beyond a predetermined amount.

CYRIL J. BATH. 

